(Mahdiarnt) wrote in message . com...
I think that I should correct myself. In the first alternative, the
space-like geodesic should be normal to the world-line of the
observer, too. Otherwise it will not be unique.

I think it is important to undertand when spacetime is flat.

If there are a absence of gravitational waves, then this would be so.

If you look at Gaussian coordinates, you get a sense of the higher
geometires. IN undertanding the metric and the relationship of quark
to quark measures, become distictive in separation.

Hope that helps.

Sol